Fischer-Tropsch synthesis (FTS) as well as many other gas-to-liquid (GTL) reactions are typically executed at high pressures (e.g. 10 atm-30 atm) and low temperatures (e.g. 200° C.-350° C.). Because of the high pressure and strong exothermic nature of FTS, fixed bed FTS reactors are typically shell-and-tube type, with many thin tubes located inside a large shell.
The FTS reactant, called synthesis gas or syngas, passes through thin tubes packed with catalyst particles, while a coolant, commonly pressurized hot water, passes through spaces between the thin tubes inside the shell. The pressurized hot water inside the shell removes heat generated from the FTS reaction to keep the reaction temperature constant or prevent wide temperature fluctuations. The circular cross-sectional area of the thin tubes along the length of FTS reactors distributes pressure isotropically along the walls of the reactor, to reduce or prevent deformation of the tube.
However, for a typical FTS shell-and-tube reactor, less than 50% of its volume is utilized for the FTS reaction.
Micro-channel reactors commonly use a cross-flow design, where the syngas and coolant flow perpendicularly to each other. However, their channel dimensions are up to 1 cm (10 mm), requiring the use of a large number of channels. See, e.g. U.S. Pat. No. 7,084,180 to Wang, et al., and U.S. Pat. No. 9,359,271 to LeViness, et al. Further, in LeViness, the catalyst in the channel reactors is in the form of a thin catalyst film wash-coated on the channel, which decreases the catalyst volume fraction to 2-4% of the shell volume. At this low catalyst loading level, process intensification is difficult to achieve.
U.S. Pat. No. 8,444,939 to Bowe and Lee-Tuffnell describes channel reactors with alternating reaction and cooling channels. However, these reactors are expensive and challenging to produce, as they require many channels and many channel connections. The catalyst is dispersed on a corrugated substrate. The corrugated structure further creates smaller, individual channels along the length of the reactor, which prevents radial diffusion of fluid flowing through the reactor. This results in low heterogeneous contact efficiencies, poor heat transfer, and the development of hotspots within the channel.
There is a need for improved channel reactors, particularly ones that permit reactions to be carried with improved process intensification.
Therefore, it is an object of the invention to provide channel reactors with improved process intensification.
It is another object of the invention to provide channel reactors with improved shell volume utilization, catalyst loading capacities, heat exchange efficiency, or combinations thereof.
It is a further object of the invention to provide improved methods and processes for conducting industrial scale chemical reactions, particularly exothermic reactions.